I realize that this thread turned nasty, but there is time to turn it around.
When FD K4FDS and I bought went out and 91AD's to play with, we immediately started looking for ways to connect them to our computers to send "data" back and fourth. In our basic testing, we used HyperTerminal and simply sent "text messages" back and fourth. What we found was, when you were talking on the radio and sending "data" at the same time, the radio would buffer up the data received at the serial port and then send it when you dekeyed. Do the radios still function this way? From what Wes said, it sounds like there is a way to simultaneously "talk" and send "data" at the same time.
Based on this VERY simple testing, we wondered if there was a way to send "APRS" packets much in the way that Wes described. Simply send the full string to the serial port of the radio. I guess it would be a non-KISS way of doing it. We could even stick some kind of ASCII flag on each end of the "frame". From our testing, we knew that the data sent in was displayed on the other end. The drawback here is the need for external hardware to do this. So, for starters, we would have to look at doing this with external computers to run a true "APRS"-like protocol.
In addition, the HamHUD project was approached by Icom to create an external terminal that was intended for marrying up with the Icom D-Star radios for an APRS-specific application of the D-Star protocol. I was involved with the initial discussions, but it was turned over to Steve Bragg KA9MVA soon after. I can't give anymore details than this because I do not have Steve's permission to do so. Needless to say, the project did not take off. Again, I cannot reveal the reasons without Steve's OK.
Jason KE4NYV
RPC Electronics
www.rpc-electronics.com